Ahh, now I get what you mean! It took me a minute of just staring at the picture before I got it
I don't have that problem, but clearly there's a picture somewhere that came with that theme which is overlapping the album art. Either you find the script and change it or you can find the file and rename it. The latter method is sloppier of course, but on the other hand it's simple and easily reversible if you know little about scripting.
Just look for picture files inside your foobar folder until you find the culprit.